Method of forming a granite roll



Feb. 19, 1963 E. OWEN 3,077,640

METHOD OF FORMING A GRANITE ROLL Filed June 15, 1960 2 Sheets-Sheet 1INVENTOR: Em m Owen ATTYS.

Feb. 19, 1963 E. OWEN METHOD OF FORMING A GRANITE ROLL 2 Sheets-Sheet 2Filed June 15, 1960 INVENTOR: Em yn Owen BY u/y W ATTYS.

3,677,640 METHGD 03F FURMENG A GRANITE ROLL Emlyn Owen, Bury, England,assignor to Walmsleys (Bury) Limited, Bury, England, a British companyFiled June 15, 196i Ser. No. 36,281 Claims priority, appiication GreatBritain Italy 7, 1%59 3 Claims. (Q1. 18-59) This invention concernsimprovements in and relating to the method of forming a granite roll.More particularly it relates to the manufacture of granite press rollsfor paper making machinery.

One object of the present invention is to provide a satisfactorysubstitute for natural granite, both for the manufacture of new pressrolls and for the repair of existing rolls from natural granite.

Another object is the provision of a method for prefabricating papermaking machine press rolls from synthetic granite, by shrinkingindividual sections onto a former.

According to the present invention, synthetic granite is made by coldcasting under pressure of a setting mixture composed of natural graniteparticles and a synthetic resin cement. The granite is preferably mixeddry with acrylic resin powder and a setting liquid is introduced intothe dry mixture. Thereafter the wet mixture is packed into a mould towhich pressure is applied for a sufr'icient time to enable curing orhardening to take place. Also according to the present invention theperipheral surface of a paper making roll is cast in the cold byapplying to a central core or roll former a setting mixture composed ofnatural granite particles and a synthetic resin cement, the mixturebeing compacted under pressure on to the core or former until curing orhardening has taken place.

This process may be adapted to build up a synthetic granite roll on ametal core or roll former by cold casting short annular sections of thesynthetic granite around the metal progressively, a suitable adhesive orhinder being included between the successive sections. Alternatively thesynthetic granite may be cold cast around an existing granite orsynthetic granite roll for the purpose of increasing the roll diameter.Again, cracks or worn portions of a granite or synthetic granite rollmay be repaired by cold casting therein or thereon synthetic graniteaccording to the present invention.

According to the present invention, the process is performed by using anapparatus for cold casting a synthetic granite surface on paper makingmachinery rolls comprising a support wherein is locatable a central coreor roll former, and an annular mould chamber movable along guide membersextending from said support to define, with a core or roll formercarried by said support, an annular space adapted to receive a settingmixture composed of natural granite particles and synthetic resincement, a pressure-exerting member being provided on the said guidemembers and capable of entering said annular chamber for the purpose ofcompacting the setting mixture contained therein.

The invention will now be further described by way of example, withreference to the accompanying drawings, in which:

PEG. 1 shows a longitudinal section through an apparatus according tothe present invention for cold casting the granite press rolls for papermaking machinery, the section being taken along the line I-l of H6. 2;

FIG. 2 is an enlarged vertical cross section taken along the line ll-llof FIG. 1, and FIG. 3 a general perspective view, partly broken away,illustrating the building up of a synthetic granite roll using themethod of the present invention.

Referring to the drawings, a synthetic granite faced press roll for apaper making machine is built up on a steel or cast iron roll center orbody 1%. As shown in FIGS. 1 and 2 of the drawings, the syntheticgranite facing has not yet been applied to the roll body, but FIG. 3shows several sections 26 of synthetic granite already applied to theroll body.

During application of the synthetic granite facing to the roll body 10,the latter is held in a vertical position by location of the backsidejournal 11 of the body in a stand 25 (see FIG. 3). A lug or eye 27 isprovided at one end of the roll body iii) to facilitate lifting andlowering. At the lower end of the roll body it), when it is in itsvertical position, a base plate 12 is arranged in abutting relationshipto the main part of the body. Around its periphery base plate 12 carriesa plurality of upstanding guide members in the form of threaded shafts13 which extend along the whole length of the main part of the roll body1t) in spaced relationship to the external periphery thereof. in theillustrated example three guide members 13 are shown. At their upperends the guide members 13 are received in the topflange of a collar 14which is held on to the top end face of the roll body 16 by means ofstuds 15 extending through the collar 14 and engaging in tapped bores 16provided in the end face of the roll body it). Nuts 17 provided on guidemembers 13 and clamped down on to the end face of collar 14 hold theguide members 13 rigid in spaced relationship to the roll body it).

An annular mould 18 (FIG. 1), having an inner diameter correspondingsubstantially to the desired outer diameter of the finished syntheticgranite faced roll before machining thereof, has an outwardly directedflange 19, which is provided with clearance holes arranged forco-operation with the guide members 13, so that the mould 18 can slidealong the guide members, and so that an annular chamber 2d for receivingthe synthetic granite is defined between the outer periphery of the rollbody 1d and the inner surface of the mould 18. The mould 18 is locatedin any desired position along guide members 13 by suitable adjustment ofnuts 21 and lock nuts 22. FIG. 1 illustrates mould 18 in position forforming a first or initial section of synthetic granite facing, whereasFIG. 3 shows it positioned for forming an intermediate section.

Also engaging guide members 13 is a compacting member 23 which has aninternal diameter which is only slightly greater than the externaldiameter of the roll body 1h, so that, as it is moved along guidemembers 13, it constitutes a close fit on the roll body (see P16. 1).That part of the compacting member 23 which is nearest to the mould 18is of such a shape and size as to just fit within the annular chamber 29defined between the mould 18 and the roll body 19, so that movement ofthe compacting member 23 along guide members 13 towards the mould 18will cause consolidation or compaction of any material contained in theannular chamber 2%.

By use of the elements 18 to 23, the synthetic granite is built uparound the periphery of the roll body 19 in individual sections ashereafter described. Bearing in mind that the roll is in a verticalposition during this process, the compacting member 23 is withdrawnupwardly along guides 13 to enable the annular chamber it to be filledfrom the top with the synthetic granite mixture referred to in greaterdetail hereafter. During introduction of this mixture to the chamber 20,care is taken to ensure that no air spaces are left, i.e. the mixturemay be tamped down. As soon as the chamber 2i; has been filled, thecompacting member 23 is moved along guide members 13 until it comes intocontact with the mixture. Thereafter, nuts 24- on guide members 13 arescrewed down so that the annular portion of the compacting member 23 isforced into the annular chamber 24), thereby consolidating the syntheticgranite mixture and placing it under considerable pressure. Levels 23may be placed on theupper face of member 23 to ensure even tightening ofnuts 24. The pressure exerted by member 23 is maintained for sufficienttime to enable the synthetic granite mixture to harden or cure.Thereafter compacting member 23 is withdrawn along guide members 13 andy adjustment of nuts 21 and 22 the mould 18 is moved along the roll bodyto expose the newly formed portion 26 of synthetic granite covering andto define a fresh annular chamber 20 for reception of a further quantityof the synthetic granite mixture. The previously formed portion ofsynthetic granite facing constitutes a bottom for the next annularchamber20. Prior to introducing the synthetic granite mixture for thenext section ofthe roll facing, an adhesive or joining solution isapplied to the end face of the previously formed section. In this way asynthetic granite facing is progressively built up in sections 26 alongthe roll body 10.

In the production of a press roll having a length of 109" and a diameterofapproximately 22", it was found convenient to build the roll in twentyindividual sections 26. It has been found that a mould 18 of adepth ofapproximately 7" is suitable in constructing synthetic granite facedpress rolls. This means that the original length of the annularchamberZt) is 7", but, assuming the full length of the chamberto beinitially filled with synthetic granite mixture, after thecompactingmember 23 has been forced down into that chamber, its length is reducedto approximately 6".

It will be appreciated that although the embodiment described refers tothe compacting member as being tightened down manually, it is possiblefor the necessary pressure to be applied pneumatically or hydraulically.

In view of the fact that the sections are built up whilst the roll body10 is in a vertical position, there is-no tendency for the mixture tospill out of the annular chamber 2%) after it has been introducedtherein.

Conveniently the outer periphery of the metal roll body 10 is roughenedor profiled to enable the synthetic granite more readily to keythereonto. On hardening or curing, synthetic granite tends to shrinkslightly in the order of .0017" per inch and the facing therefore keysitself on to the body 16 during the hardening or curing action.

The profiling of the roller body 10 can be effected by circumferentialor longitudinal machining to give a rough finish. Alternatively, theroller body may have grooving formed therealong or therearound.

If desired, it is possible to introduce reinforcement, such as steelhands of hoop iron, into the individual sections of the syntheticgranite as they are applied to the roll body 10, this reinforcementbeing embedded in the synthetic granite so as to lie below the finishedsurface of synthetic granite.

After the completed roll has been built up in sections, it is thenfinished by turning with a tungsten carbide tool. The synthetic graniteis given a constitution such that it has a slightly porous surface, suchporosity being more or less essential to enable the paper to leave theroll without excessive adhesion.

Preferably in the mix for the synthetic granite there areeight-and-one-haif parts of granite dust to one part of resin by Weight.For instance, a suitable mix for the synthetic granite is as follows:

1 lb. of granite dust .12 lbs. of acrylic resin. (This is conveniently apowder in the form of polymerized methyl methacrylic acid, suitablyprepared for the doughing and hardening characteristics required, thepowder containing one of the components of a suitably selected redoxsystem, to ensure the polymerisation of the monomer at ambienttemperature) 89 cc. of cement, such as a cold setting methylmethacrylic, or a polymerized methyl methacrylic 22 cc. of a hardeningsubstance, such as stabilized methacrylic acid.

For the 109 long and 22" diameter roll referred to above, it was foundthat the following amounts of synthetic granite mixture were requiredfor each 7 section of facing (compacted to 6").

19 lb. 2 oz. of granite dust 21b. 4 oz. of acrylic resin 1710 cc. cement428 cc. hardening substance.

With the synthetic granite mixture referred to above, it has been foundthat each section takes approximately 45 minutes to harden or cure, andat the end of that time it is possible to withdraw the compacting member23 and move the mould 18 up in preparation for production of the nextsection.

A suitable jointing solution for application between successive sectionsofthe synthetic granite facing is pro duced by mixing 21 grams of apaste, ofbenzoyl peroxide in phthalate plasticiser 50% paste, with cc.of-methyl methacrylic monomer catalized with dimethyl-para-toluidine.

To obtain the necessary porosity, it is desirable to ensure that thegranite dust particles are of a suitable size. This may be achieved byusing granite dust which conforms to a sieve test as follows:

It will be seen by reference to FIGS. 1 and 3 of the drawings that thetop collar 14 extends the guide members 13 beyond the main part of thebody 10, thereby enabling the compacting member 23 to be moved along theguide members 13 to a sufficient distance to enable the mould 18 to belocated around the end (top) section of the roll body 10 and slightlyprotruding therefrom, thereby allowing compaction of the final sectionof synthetic granite to bring it into line with the end face of theroll.

Once the end section of synthetic granite has been applied and cured orhardened, then the elements 12 to 23 are removed and the roll is dressedwith a tungsten carbide tool and finished with coarse and fine grindingwheels.

If desired, the outer peripheral ends of the roll body 10 may beundercut, for instance in the form of a dovetail, so that an additionalkeying of the synthetic granite surface to the roll body is achieved,over and above the shrinking-on of each section inherent in the curingor hardening of the synthetic granite.

It has previously been proposed to manufacture a roll wherein the activesurface is formed by pieces of rock bound together with a rubber orrubber compound. Such a construction has proved unsatisfactory, byvirtue of the Wide variation between the wearing properties of the rockand the rubber hinder, the latter tending to disintegrate much morerapidly than the rock with the result that the pieces of rock wereloosened or evenseparated from the roll surface causing considerabledamage to material passing over the roll. The present inventionprovides, for the first time, a synthetic granite wherein the resinousbinding material exhibits wearing properties commensurate with that ofthe granite particles which are embedded therein. Moreover, by providingthe granite constituent of the substance in dust form rather than inparticulate, discrete or lumpy pieces, the tendency for uneven wear witha synthetic granite facing according to the present invention is furtherreduced.

A major advantage of the synthetic granite facing of the presentinvention is that the porosity of the roll surface can be adjusted aspreviously mentioned, and this of course is not possible with naturalgranite rolls. Neither can it be obtained when a rubber bin-ding agentis employed, as the rubber, being impervious to moisture, produces asurface on the roll which has an uneven porosity.

By building up a roll surface of synthetic granite in individualsections according to the present invention, any tendency for the rollto crack or fracture along its length is greatly reduced. Certainly anyfault is localized, inasmuch as development of a crack or fracture isarrested on reaching the boundary of any individual section. In view ofthe above, a paper making machine roll according to the presentinvention is better able to withstand or absorb stresses than is a rollprovided with a one-piece facing.

I claim:

1. The method of forming a granite roll for a paper making machine usingan annular mold shorter than the roll comprising the steps of forming afirst annular ring of a mixture of granite particles and synthetic resincement within the mold around a core, said ring being of a length lessthan the core and holding the mixture to a cylindrical shape andcompacting it axially, permitting the first ring to set to a sufiicienthardness to support an axial force of compacting a second ringthereagainst, applying "a joining material to an end face of the ring,thereafter moving the mold axially and forming a second annular ring ofa mixture of granite particles and synthetic resin cement around thecore against the end of the first ring with said joining materialtherebetween, and similarly forming successive annular rings along saidcore each with a layer of joining material joining it to a previous ringto complete -a roll.

2. The method of forming a granite roll for a paper making machine usingan annular mold shorter than the roll comprising steps of dry mixingnatural granite particles with an acrylic resin powder to form amixture, forming a first annular ring of said mixture within the moldaround the core, said ring being of a length less than the core, andholding the mixture to a cylindrical shape compacting it axially,permitting the first ring to set to a suflicient hardness to support anaxial force of compacting a second ring thereagainst, applying a joiningmaterial to the end face of the ring, thereafter moving the mold axiallyand forming a second ring of said mixture against the end of the firstring with said joining material therebetween, and similarly formingsuccessive annular rings of the mixture along said core each with alayer of joining material joining it to the previous ring to complete aroll.

,3. The method of forming a granite roll for a paper making machineusing an annular mold shorter than the roll comprising the steps offorming a first annular ring of a mixture of granite particles andsynthetic resin cement within the mold around a core, said ring being ofa length less than the core and holding the mixture to a cylindricalshape and cold casting the mixture under pressure permitting the firstring to set to a sufiicient hardness to support an axial force ofcompacting a second ring thereagainst, applying a joining material of anadhesive substance to an end face of the ring after said ring has set,thereafter moving the ring axially forming a second annular ring of amixture of granite particles and synthetic resin cement around the coreagainst the end of the first ring with said joining materialtherebetween, and similarly forming successive annular rings along saidcore each with a layer of joining material joining it to a previous ringto complete a roll.

References Cited in the file of this patent UNITED STATES PATENTSRe.17,740 Martin July 22, 1930 226,013 Allen Mar. 30, 1880 228,034Detr-ick Nov. 6, 1883 1,074,983 Sborowitz Oct. 7, 1913 1,624,904 ClausApr. 12, 1927 1,787,890 Woodward Jan. 6, 1931 2,110,143 Ball et a1 Mar.8, 1938 2,605,533 Hirsh Aug. 5, 1952 2,883,703 Frank Apr. 28, 19582,983,990 Stevenson et al. May 16, 196 1

1. THE METHOD OF FORMING A GRANITE ROLL FOR A PAPER MAKING MACHINE USINGAN ANNULAR MOLD SHORTER THAN THE ROLL COMPRISING THE STEPS OF FORMING AFIRST ANNULAR RING OF A MIXTURE OF GRANITE PARTICLES AND SYNTHETIC RESINCEMENT WITHIN THE MOLD AROUND A CORE, SAID RING BEING OF A LENGTH LESSTHAN THE CORE AND HOLDING THE MIXTURE TO A CYLINDRICAL SHAPE ANDCOMPACTING IT AXIALLY, PERMITTING THE FIRST RING TO SET TO SUFFICIENTHARDNESS TO SUPPORT AN AXIAL FORCE OF COMPACTING A SECOND RINGTHEREAGAINST, APPLYING A JOINING MATERIAL TO AN END FACE OF THE RING,THEREAFTER MOVING THE MOLD AXIALLY AND FORMING A SECOND ANNULAR RING OFA MIXTURE OF GRANITE PARTICLES AND SYNTHETIC RESIN CEMENT AROUND THECORE AGAINST THE END OF THE FIRST RING WITH SAID JOINING MATERIALTHEREBETWEEN, AND SIMILARILY FORMING SUCCESSIVE ANNULAR RINGS ALONG SAIDCORE EACH WITH A LAYER OF JOINING MATERIAL JOINING IT TO A PREVIOUS RINGTO COMPLETE A ROLL.